1. Field
The following description relates to a wireless power transmission system and a method for increasing a coupling efficiency by adjusting a resonant frequency.
2. Description of Related Art
A wireless power transmission technology enabling a power supply without using a power line has been increasingly spotlighted. When the wireless power transmission technology is commercialized, energy may be easily supplied to a wired charging system. The wireless power transmission technology may enable charging at any time and anywhere, and may be a first step toward an environment enabling sharing of a power source between devices without a power source.
Wireless power refers to energy that is transferred from a wireless power transmitter to a wireless power receiver, for example, through magnetic coupling. A wireless power transmission system includes a source device and a target device. The source device wirelessly transmits a power, and the target device wirelessly receives the power. The source device may be referred to as a wireless power transmitter, and the target device may be referred to as a wireless power receiver.
The source device includes a source resonator, and the target device includes a target resonator. Magnetic coupling or resonance coupling may be formed between the source resonator and the target resonator.
When a satisfactory coupling efficiency is not secured due to a long distance between a source device and a target device, at least one relay resonator may be inserted between a source resonator and a target resonator, which may result in an increase in the coupling efficiency. In this example, a device including the relay resonator may be referred to as a relay device. The same resonant frequency may be used in all of the source resonator, the target resonator, and the relay resonator.
However, it is difficult to guarantee an optimum coupling efficiency, due to a gap between resonators, an arrangement of the resonators, different quality factors of the resonators, and/or other factors known to one of ordinary skill in the art.